Antibodies are composed of heavy chains (H chains) and light chains (L chains). The heavy chains and light chains are composed of a variable region (VR) and a constant region (CR), and the variable region has a complementarity determining region (CDR). Moreover, antibody light chains are classified into κ chains and λ chains.
In recent years, attention has been focused on antibodies having an enzyme-like activity, namely, antibody enzymes. Since antibody enzymes have both the ability of antibodies to accurately recognize molecules and the activity of enzymes, they are expected to be applied in numerous fields, including medicine, the chemical industry and the food industry. In particular, since antibody enzymes exhibit high specificity for a target molecule and are able to impair target molecules due to their enzyme activity, they are expected to serve as superior anticancer agents that demonstrate few adverse side effects.
The inventors of the present invention have heretofore conducted various innovative research on antibody enzymes (see, for example, Patent Document 1). Antibody enzymes having complete human sequences have conventionally been unable to be obtained with the exception of the Bence-Jones Protein (BJP) obtained from multiple myeloma patients. Since there are few multiple myeloma patients and only a small amount of BJP that has enzyme activity, it was difficult to acquire a human antibody enzyme. However, since human antibody enzymes are predicted to demonstrate few adverse side effects when administered to a human body, pharmaceutical companies both at home and overseas are awaiting the development of a useful human antibody enzyme.